| 摘要 |
PURPOSE:To attain ease of tracking control by irradiating a spot of linearly polarized light to a recording track and a tracking track and detecting a DC component of both differential outputs obtained through an analyzer. CONSTITUTION:Laser light is split into three, converting them into linearly polarized light by an analyzer, and three spots 15-17 are irradiated through an objective lens so that the center spot 16 is projected to the center of a recording track 12 and the spots 15, 17 are projected to a half to the recording track 12 and the tracking track 13. The main signal is optically reproduced by the central spot 16. The reflected light of the spots 15, 17 is detected by photodetectors 18a, 18b, its output is inputted to a differential amplifier 19, only the DC component is obtained from the differential output via an integration circuit (LPF)20, and a tracking device (e.g., objective lens) 22 is subject to tracking control via a tracking drive circuit 21. |
